Hydraulic turbine



July 1, 1930. L.. F:j MooDY 1,769,887

HYDRAULIC TURBINE Original Filed Nov. 13, 1925 ii l \ INVENTOR a BY E jA44* A ORNEYJ Patented duly l, i3@

HYDRAULIC TURBINE iOriginal application filed November 13, 1923, SerialNo. 674,461, and in Canada October 16, 1924. Divided and thisapplication filed April 16, 1926,

rli-"nis invention relates to hydraulic turbines and particularly todraft tubes for the same. T he object of the invention is to provide adraft tube which while simple and inexpensive in construction will beeilic'ient in operation and especially adapted to decelerate the flowwithin a limited space. Another object of the invention is to provide adraft tube suitable for turbines of high specilic speed.

Further objects ofthe invention. particularlyY in providing a draft tubestructure hava series of concentric annular passages in position belowthe runner, will appear from the following description and theaccompanying drawings.

By dividing the draft tube passage into a number of passages eachreceiving a part of the total flow7 it becomes possible to deceleratethe velooityof discharge from the runner and to convert its kineticenergy into useful head within a smaller space than would be'possible ifsingle passage-were used, and to accomplish this wit-hout sacrifice ofdraft tube eiliciency. The reasonwhy thisr can beaccoinplished maybeunderstood by considering a simple passage of rectangular cross-sectionhaving a pair of opposite `sides diverging at a small angle. Such apassage will decelerate the flow, and it is known that the eiiiciency ofthe energy conversion is dependenton the angle of divergence of thesides. lf the angle is increased beyond the best value in the effort toproduce the deceleration in a shorter length of passage, internal eddiesare caused in the flow and the efticiencyof conversion is iinpaired. l@however. a partition is interposed midway between'the diverging walls,the angle of divergence between the partition and each wall is cut inhalf; and each of the ne passages thus formed may have the mostfavorable angle of divergence, and the outer walls of the o ginalpassage will then have twice the angle of divergence which would 'bepermissible without thepartition. rlfhis princi e of securing rapiddeceleration within a restricted length of passage by subdivision whenapplied to conical or flaring annular passagesj results in the forms ofdraft tubesA described herein.

SerialNo. 102,494. Renewed. November 12, 1928.

ln the specific embodiment of the invention shown in the drawings, Y

Fig. l is a vertical section of a turbine installation embodying theinvention,

Fig. 2 is a vertical sectional view of a turbine unit,

3 is a fragmentary sectional view` of a modified form of the invention.

In the turbine shown in the drawings a floor 48 extends downstream'froin the head water H and above this floor is an entranceforming an admission' pas' space or flume E sage leading the water tothe turbine and eX- tending above and around the fixed guide v'anesw 36providing the entrance tothe turbine. The fiow passing in through theseguide vanesBG and down through the runner ll is discharged into thedraft tube emptying downwardly and'outwardly into a discharge chamber Dleac in to'tailwater T. The outer wall of the draft tube is formed as aliner casting 53 embedded in the concrete of the floor 4S and at itslower end this liner 'castin g carries theprojecting extension 53 ofgenerally conical formand constructed ofplate metal bent into the formof a skirt suspended from said casting 52. Ilhe central conical core iissimilarly formed of plate metal bent into the form shown and providedwith a cap member 55 under the hub of the runner rlhe intermediatepartitions 56, 57 are similarly formed of a series of plate sectionsbent into generally conical form and nested oneover the other bylapjoints as shown. All' of these plate metal members are connectedtogether by the straps or stays 60 at their discharge edges. These staysmay be inclined as shown to suit the direction of flow. The flow fromthe runner is received in a substantially axial direction and turnedoutward toward a radial direction and decelerated in the upper portionof the draft tube. and in the lower portion of the draft tube the flowis spread and decelerated all around between concentric conical walls.

This plate metal construction ofthe draft tube is inexpensive and easilyformed and gives a higher rate of deceleration of the outflow within asmall space (see Fig. l) `being suspended from the .floor 48 of theflume.

This draft tube permits the outlet chamber 58 to be of any desired formand, where delired, the central conical core 54 may be continued down tobe supported from the floor 5 of this chamber as indicated at 59, or inthe modification shown in Fig. 3 the core 54 may terminate short of thefloor thereby being of substantially the same length as the partitions.

The intermediate partitions 56, 57 individing the draft tube into aplurality of passages permit a higher rate of deceleration withoutdeparture ofthe flow from the draft tube surface, because each passagecan have thepermissible rate of increase in area independently of theother passage and the i permissible rateof increase in area is us aproximately tripled, according to the gincipepreviously explained. Thismakes 1 possible to accomplish the desired decelerapgtheow wit in a muchshorter length o draft tube, reducing the size and cost of thestructure. The walls 52, 53, 54, 5c, 57 formadas surfaces of revolutionoffer nollistruction to the whirling components of the outflow, and bysmoothly spreading and turning thisoutiow the annular draft tube L`formed by the annular wallsthereo are adapted to recover both themeridian whirling components of velocity.

.While the draft tube of this invention is app 'cable to turbines of allty s, it is part1 ,ly advantageous for tur ines of high ds, such as thepropeller type illBS Own in the figures. In turbines 'i .ind Ilideratespecific1 speeds there is ,l f ten eney at artia gate openings to tageplace through only l, Plitpf the runner, namely, that near the latenterperiphery. The draft tube thus reogives a ring of downward flowing water`blind its outer wall, the inner portion being to water not progressingdownward but subjectto local turbulence and, near the axis, to u wardHow into the runner. In turbines of high specific speed, this tendencystill, more pronounced, and takes effect mnoagh alarga range of gateopenings and normal gate insuch turbines the fiow than the runner may bevery unequally uted. Attempts to improve the turbilieperformance bysubdividing the runner by the addition of intermediate shroud ringsol'fdiaphragms in order to separate the flow intofdistinct annularvzones have not shown any material improvement; and in high sp'lhspeedturbines such diaphragms in the'i er are very objectionable from the n tipcrease in surface friction which they tothe high relative velocitybewegnerunner and the water.` I thereat', (d he use f any shroud rinfgsor dia- Qi turbines of high speci c speed' la ina tragitto"improvthcondaions in th tance from the axis in passing from the en'trance to the discharge of the passage, I obtain a tube in which thecentrifugal force of the contained water sets up an outward pressure andmaintains a low pressure at the runner discharge. I also provide a solidcore in the central ortion of the tube to avoid the extreme conditionsof whirl and inefficient flow, and even the creation of a cavity, whichvare likely to occur near the axis.

t When small space and reduced first cost are of great importance, as inlow or medium head plants, the form of tube shown in Figs. 1 and 2 maybe used, in which the innermost passage is not carried to as great aradial distance from the axis as the outermost, but a large total areaof discharge for the entire draft tube is provided within a small space.Inthis form of tube the discharge takes place through almost the wholeof the portion of the spherical surface bounded by the discharge edge ofthe outer wall of the draft tube, the only art of this area which is notutilized for t e discharge How being the relatively small area of thebase of the cen tral core, and the space taken up by the thickness ofthe metal in the partitions.

In one aspect of the invention the draft tubeacts as a diffusin nozzlefor converting the tvelocity of ilui into pressure by the provision ofpassages the opposing walls of which enclose angles of substantially 10.This is the case between the lower sections 53, 56 and 57, thesesections comprising a substantial portion of the whole draft tube. Thisresults in a multiple passage arrangement having a total outlet apertureor area considerably larger than that which could be obtained with asingle passage nozzle having the same length and the same size of inletorifice.

The structure of this invention provides a turbine of simple andinexpensive form and of small overall dimensions. The suspension of thedraft tube from the intake floor avoids the necessity of any specialformation of the outlet passage and the short length of the draft tube`is particularly adapted for shallow outlets requiring only a limiteddepth of excavation.

Thisqapplication is la` division of my copending application Serial No.674,461, filed November 13, 1923.

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y Y' I claim z` l. ln a hydraulic turbine, the combination with a.ruimer of a draft tube having an outer Wall Haring outwardly aWay fromthe axis and one or more relatively thin intermediate partitionssubdividing the flow and formed with surfaces curved from asubstantially axial direction at entrance to directions which divergefrom the axis at discharge, the angle of divergence being greater in thepartitions more remote from the axis Vand said partitions havingsuccessively greater discharge diameters.

2. in a hydraulic turbine,the combination with a runner of a draft tubehaving an outer Wall diverging from the axis and one or more relativelythin intermediate partitions subdividing the flow and formed withsurfaces curved from-a substantially axial direction at entrance toYdirections Which diverge from the axis atdischarge, the angle ofdivergence being greater in the -partitions more remote from the axisand the discharge portions of said partitions forming a series ofco-axial straight-sided cones.

3. In a hydraulic turbine the combination With a runner of a draft tubecomprising a central core and a plurality of annular passagesconcentrically disposed around said core, said core being continuous incontour With the runner hub, and said passages having approximatelyequal lengths When measured in the direction of the meridian componentsof the'liovv.

- 4. In a hydraulic turbine the combination with a runner of a drafttube comprising a central core, a plurality of concentric annularpassages surrounding said core, and an outer Wall flaring fromsubstantially axial direction toward a radial direction, said corehaving a diameter at the discharge end less than onethird the diameterof the outer Wall to provide a lcore Which occupies a relatively smallportion of the total discharge area.

' 5. ln a hydraulic'turbine the combination with a runner of a dischargepassage, a draft tube comprising a central core extending to the floorof said discharge passage and supported thereby, and plate metalpartitions of substantially uniform Vthickness forming a plurality ofannular passages-concentrically disposed around said core, havingapproximately equal lengths Whenmeasured inthe direction of themeridian'components of the flow. Y

6. VInV a hydraulic turbine the combination with a krunner of a drafttube comprising a central core, and a plurality of annular passagesconcentrically disposed around said core, said core being continuous incontour With the runner hub and in'close proximity thereto, andsaid'passages having approximately equal lengths AWhen measured in the(lirection of the meridian components of the 7. A draft tube for ahydraulic turbine comprising a central core excluding the flow from thecenter of the tube and the surface of the core having a substantially'axial direction at the discharge from the runner, an outer Wall flaringfrom substantially axial direction toward a radial direction, and one ormore intermediate partitions of plate metal construction havingsubstantially uniform thickness, and said partitions dividing the flowinto a series of concentric annular passages.

8. A draft tube for a hydraulicturbine comprising a central core and aplurality 'of concentric annular passages surrounding said core, theWalls of said passages being substantially axial at entrance, and thelength of the innermost passages measured in a meridian plane and in thedirection of flow being substantially equal to that of the outermostpassage.

9.k ln a hydraulic turbine having a runner the combination With a floorstructure, of inclined stay vanes supported thereby and carrying abearing structure for the runner shaft, a draft tube receiving the flowfrom sra-id runner and comprising a plurality of concentric plate metaltubes spreading outward and'dividing the flow into a plurality ofspreading annular streams, the inner tubes being supported from theoutermost tube lwhich in turn is supported from said floor structure.

l0. ln a hydraulic turbine having a runner the combination with asub-foundation structure forming the. top of a discharge passage, of adraft tube projecting downward into said passage and comprising a seriesof concentric tubes of plate material and of generally conical formdiverging outward from a central axis, the angle between successivecones with respect to each other being relatively small so that theangle of divergence of the tubes progressively decreases from arelatively large angle for the outer tube to a relatively small anglefor the innermost tube. ll. ln a hydraulic turbine installation thecombination with a floor structure, of means thereabove forming anentrance passage or flume, a passage through said floor structure, anunshrouded propeller type runner in saidV passage, inclined fixed guidevanes supported from said floor structure above said runner and formingadmission means to said turbine passage, said entrance passage or flumeextending above andy around said admission means, and a plural Apassagedraft tube for said runner forming continuation of the passage in saidfloor.

l2. In a hydraulic turbine installation the combination with a floorstructure, of means f thereabove forming an entrance passage or flume, apassage through said floor structure, an unshrouded rpropeller typerunner in said passage, inclined fixed guide vanes supported from saidlicor structure and supporting a CLI boring for the shaft of said runnerAand pro- Willing admission `means to said turbine passage, saidentrance passage or flume extending above and around said admissionmeans to permit flow of fluid thereto simultaneously from radial andaxial directions, and a plural ge draft tube extending from the openmgin said floor.

18. In a hydraulic turbine installation the combination with a floorstructure, of means thereabove forming an entrance passage or flume, apassage through said floor structure, sa unshrouded propeller typerunner in said passa fixed guide vanes supported from said' oorstructure above said runner and,

gadmission means to said turbine passage, `said entrance passage orflume extending above and around said admission means to permit flow offluid thereto simultaneously from radial and axial directions, and aplural passage draft tube leading from said turbine pesage and suspendedfrom said floor structure.

`14. In a hydraulic turbine installation the combination with a floorstructure, of means thereabove forming an entrance passage or flume, apassage through said floor structure, anunshrouded propeller type runnerin said plunge, fixed guide vanes supported from said; oor structureabove said runner and forming admission means to said turbinepassogovsaid entrance passage or flume extendingabove and around saidadmission means tr'letmit of fluid thereto simultaneously from al andaxial directions, and a plural passheet metal draft tube leading fromsaid turbine passage and suspended from said door structure.

15. In a hydraulic turbine installation the combination with a runner,of a draft tube cmprisin a. central core having a contour substantia lycontinuous with that of the runnorhub and in relatively close proximitythereto, and means forming a plurality of annular passages disposedaround said core, the diameter of the discharge portion of said lattormeans bein greater than that of said core adjacent the scharge.

'16.` In a hydraulic turbine installation the combination with a runnerhaving a hub, of o draft tube comprising a central core having l contoursubstantially continuous with that o! the runner hub and in closeproximity thereto, and means forming a plurality of diverging annularpassages disposed around said core, the diameter of said core at thepoint of discharge being less than the discharge diameter of the meansforming said passagI.

17. a hydraulic turbine installation the combination with a runnerhaving a hub, of a draft tube com rising a central core having a contoursu stantially continuous with that of the runner hub and in closeproximity thereto, and means forming a plurality of diverging annularpassages substantially concentrically disposed around said core and saidmeans including a relatively thin plate metal member having a greaterdischarge diameter than that of the discharge portion of said core.

18. In a hydraulic turbine installation the combination with a runnerhaving a hub, of a draft tube comprising a central core having a contoursubstantially continuous with that of the runner hub and in closeproximity thereto, and means forming a plurality of diverging passagessurrounding said core, said means comprising relatively thin plate metalmembers so disposed that the general outline of said draft tube issubstantially fan shape.

19. In a hydraulic turbine installation the combination with anunshrouded propeller type runner, of a draft tube having means forming aplurality of passages surrounding a common axis, said means comprisingrelatively thin partition members of substantially uniform thicknessbetween their entrance and discharge edges whereby the discharges fromadjacent passages merge along a line which is substantially parallel toboth sides of the partition forming said adjacent passages.

20. In a hydraulic installation the combination with a turbine runner,of a draft tube comprising means forming a plurality of divergingpassages disposed about a common axis, and a core for excluding waterfrom the central portion of the tube, said means including a relativelythin plate metal member forming the partition between the adjacentpassages and said member having a discharge diameter greater than thatof said core.

21. In a hydraulic turbine installation the combination with a turbinerunner, of a draft tube including means forming a plurality ofsubstantially annular and concentric diverging passa es, said meanscomprising relatively thin p ate metal members forming inner and outerwalls and a similar member forming a partition therebetween, thediameters of said members at their discharge edges being different.

22. In a hydraulic turbine installation the combination with meansforming an entrance passage floor having a vertical opening therethroughand a turbine runner associated with vsaid Vvertical opening, of a drafttube having means forming a plurality of substantially annular andconcentric diverging passa es and said means comprising relatively t inlate metal members having a depending reation to said floor and theouter one of said members being more horizontal than vertical.

23. In a hydraulic turbine installation the combination with meansforming an inlet passage having a floor with a vertical openingtherethrough and a turbine runner associated with said opening, of meansforming a draft tube comprising inner and outer sublli , their adjacentedge incase? stantially annular and concentric members, and a partitionbetvveen said members, said outer member flaring outwardly and dependingfrom the lower surface ot said floor so as to be spaced therefrom andhaving a discharge diameter greater than that of said partition.

2li. ln a hydraulic turbine installation the combination with a runner,of means forming a draftctube comprising a plurality of substantiallyannular and concentric diverging passages, said means including apartition comprising a plurality ot substantially coaxial plate metaltubular sections having their adjacent edge portions held in operativerelation to each other whereby said tubular members form a continuationci each other.

25. ln a hydraulic turbine installation the combination With a runner,of means formg in(r a draft tube com arisino` a )luralit ofsubstantially annular and concentric diverging passages, said meansincluding a partition comprising a plurality of substantially coaxialplate metal tubular members having portions held in operative relationto each other whereby said tubular members form a continuation of eachother and certain of said tubular members are of substantially greaterlength than the length of others thereof.

26. ln a hydraulic turbine installation the combination With a runner,of means forming a draft tube comprising a. plurality of substantiallyannular and concentric diverging passages, said means including apartition comprising a plurality ot sections formed as .substantiallycoaxialr tubular members having their adjacent edge portions held inoperative relation to each other whereby said tubular members form acontinuation of each other and said sections having a greater degrec offlare as the discharge end of the draft tube is approached.

27. In a hydraulic turbine installation the combination with a turbinerunner, ot' a draft tube comprising means forming a plurality ofdiverging passages, said means comprising relatively thin plate metalmembers so disposed that the general outline of said draft tube issubstantially fan shape.

:28. ln a hydraulic turbine installation the combination With a turbineruimer, of a draft tube having means forming a plurality ofsubstantially annular and concentric divergpasages, said meanscomprising relatively thin plate metal members the outer one of which ismore horizontal than vertical.

A multiple diffusing nozzle for conver-ting the velocity of a fluid intopressure and constituted of a compound element having a plurality oitpassages each defined by uniformly diverging Walls, the opposing Twallsof each passage enclosing angles of substantially 10, the Whole to theeect that the multiple passage nozzle possesses a total outlet apertureconsiderably larger than that which could be obtained with a singlepassage nozzle having the same length and the same size or' inletorilice.

30. A high specific speed propeller hydraulic turbine comprising, adraft tube, having a main divided passage providing a plurality ofdivisional diverging passages, the opposing Walls of at least certain ofsaid divisional Y assages enclosing angles ot' substantially l0 degreesthroughout the major extent thereo, the Whole to the eect that saiddivisional passages together have a `eater outlet area than that whichcould be obtained With a. single passage having the saine length andsize of inlet for said draft tube and a propeller type runner disposedin said passage and spaced froml the entrance o'l` said draft tube toprovide a transition space therebetween.

Lilli/*XS MOODY.

type

lll() CERTIFICATE OE CORRECTION.

Patent No. 1,769,887. Granted July 1, 1930, to

LEWIS FERRY MOODY.

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,line 81, claim 30, after the word "inlet" insert the comma and words acentral core; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 21st dayof October, A. D. 1930.

M. J. Moore, (Seal) Acting Commissioner of Patents.

